Neuzil et al U.S. Pat. No. 4,048,205 and Neuzil et al U.S. Pat. No. 4,049,688 and Logan et al U.S. Pat. No. 4,210,594 disclose the fractionation of alkyl fatty carboxylate mixtures using synthetic crystalline aluminosilicates (zeolites). These crystalline aluminosilicate adsorbents typically contain up to about 25% amorphous aluminosilicate, e.g., clay. The process of the invention herein differs for example, in the adsorbent which is advantageous over the crystalline adsorbents from the standpoints of versatility (in that, with the adsorbent herein, the same equipment and packing is advantageously used for separation of alkyl carboxylates and triglycerides--this is not true for crystalline zeolites) and flexibility (in that various ratios of silicon atoms to aluminum atoms and various surface areas are readily selected for the adsorbent herein--there is substantially less choice for crystalline zeolites).
Lubsen et al U.S. Pat. No. 4,189,442 discloses the fractionation of alkyl fatty carboxylate mixtures utilizing macroreticular strong acid cation exchange resin adsorbents. The invention herein differs, for example, in utilizing an adsorbent different from that disclosed in U.S. Pat. No. 4,189,442 and advantageous over resin adsorbents from the standpoints of flexibility, cost, and of being inorganic rather than organic in nature.
It is known on an analytical scale to separate alkyl fatty carboxylate mixtures utilizing silica gel treated with silver nitrate. See Chemistry and Industry 24, pp. 1049-1050 (June 1962). The adsorbent there has the disadvantage of having a short life cycle in that the silver nitrate is leached out since it is not chemically attached. The adsorbent used herein has no such leaching problem.
British Pat. No. 1,476,511 (complete specification published June 16, 1977) which corresponds to German No. 2,335,890, assigned to Henkel, discloses using an aluminosilicate clay as an acidic catalyst to polymerize multiple unsaturated components of a mixture of esters of fatty acids and distilling to separate unpolymerized material from polymerized material. Such process has the disadvantage of producing unuseful polymerized material. The process of the instant invention is carried out without significant polymerization occurring.
Lam et al, "Silver Loaded Aluminosilicate As a Stationary Phase for the Liquid Chromatographic Separation of Unsaturated Compounds", J. Chromatog. Sci. 15 (7), 234-8 (1977) discloses the analytical (chromatographic) separation of bromophenacyl carboxylates on the basis of unsaturation utilizing silvered, surface aluminated silica gel adsorbents of microparticulate particle size (which particle size is not readily handled in a nonanalytical commercial context and can result in significant loss due to suspension of particles in solvent). The process of the instant invention differs at least in the feedstock and in the adsorbent chemical structure and in the adsorbent particle size.
Breck, D. W., Zeolite Molecular Sieves, John Wiley & Sons, New York, 1974, pages 11-13 generally describes synthetic amorphous aluminosilicates (permutites) and uses thereof. The adsorbent herein is particular permutite as described in detail below.